dm bufio: Support IO priority

Some IO will dispatch from kworker with different io_context settings
than the submitting task, we may need to specify a priority to avoid
losing priority.

Add dm_bufio_read_with_ioprio() and dm_bufio_prefetch_with_ioprio()
for use by bufio users to pass an ioprio other than IOPRIO_DEFAULT.
Co-developed-by: Yibin Ding <yibin.ding@unisoc.com>
Signed-off-by: Yibin Ding <yibin.ding@unisoc.com>
Signed-off-by: Hongyu Jin <hongyu.jin@unisoc.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
[snitzer: introduced _with_ioprio() wrappers to reduce churn]
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-bufio.c

@@ -1292,7 +1292,8 @@ static void dmio_complete(unsigned long error, void *context)
 }
 
 static void use_dmio(struct dm_buffer *b, enum req_op op, sector_t sector,
-		     unsigned int n_sectors, unsigned int offset)
+		     unsigned int n_sectors, unsigned int offset,
+		     unsigned short ioprio)
 {
 	int r;
 	struct dm_io_request io_req = {
@@ -1315,7 +1316,7 @@ static void use_dmio(struct dm_buffer *b, enum req_op op, sector_t sector,
 		io_req.mem.ptr.vma = (char *)b->data + offset;
 	}
 
-	r = dm_io(&io_req, 1, &region, NULL, IOPRIO_DEFAULT);
+	r = dm_io(&io_req, 1, &region, NULL, ioprio);
 	if (unlikely(r))
 		b->end_io(b, errno_to_blk_status(r));
 }
@@ -1331,7 +1332,8 @@ static void bio_complete(struct bio *bio)
 }
 
 static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector,
-		    unsigned int n_sectors, unsigned int offset)
+		    unsigned int n_sectors, unsigned int offset,
+		    unsigned short ioprio)
 {
 	struct bio *bio;
 	char *ptr;
@@ -1339,13 +1341,14 @@ static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector,
 
 	bio = bio_kmalloc(1, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN);
 	if (!bio) {
-		use_dmio(b, op, sector, n_sectors, offset);
+		use_dmio(b, op, sector, n_sectors, offset, ioprio);
 		return;
 	}
 	bio_init(bio, b->c->bdev, bio->bi_inline_vecs, 1, op);
 	bio->bi_iter.bi_sector = sector;
 	bio->bi_end_io = bio_complete;
 	bio->bi_private = b;
+	bio->bi_ioprio = ioprio;
 
 	ptr = (char *)b->data + offset;
 	len = n_sectors << SECTOR_SHIFT;
@@ -1368,7 +1371,7 @@ static inline sector_t block_to_sector(struct dm_bufio_client *c, sector_t block
 	return sector;
 }
 
-static void submit_io(struct dm_buffer *b, enum req_op op,
+static void submit_io(struct dm_buffer *b, enum req_op op, unsigned short ioprio,
 		      void (*end_io)(struct dm_buffer *, blk_status_t))
 {
 	unsigned int n_sectors;
@@ -1398,9 +1401,9 @@ static void submit_io(struct dm_buffer *b, enum req_op op,
 	}
 
 	if (b->data_mode != DATA_MODE_VMALLOC)
-		use_bio(b, op, sector, n_sectors, offset);
+		use_bio(b, op, sector, n_sectors, offset, ioprio);
 	else
-		use_dmio(b, op, sector, n_sectors, offset);
+		use_dmio(b, op, sector, n_sectors, offset, ioprio);
 }
 
 /*
@@ -1456,7 +1459,7 @@ static void __write_dirty_buffer(struct dm_buffer *b,
 	b->write_end = b->dirty_end;
 
 	if (!write_list)
-		submit_io(b, REQ_OP_WRITE, write_endio);
+		submit_io(b, REQ_OP_WRITE, IOPRIO_DEFAULT, write_endio);
 	else
 		list_add_tail(&b->write_list, write_list);
 }
@@ -1470,7 +1473,7 @@ static void __flush_write_list(struct list_head *write_list)
 		struct dm_buffer *b =
 			list_entry(write_list->next, struct dm_buffer, write_list);
 		list_del(&b->write_list);
-		submit_io(b, REQ_OP_WRITE, write_endio);
+		submit_io(b, REQ_OP_WRITE, IOPRIO_DEFAULT, write_endio);
 		cond_resched();
 	}
 	blk_finish_plug(&plug);
@@ -1852,7 +1855,8 @@ static void read_endio(struct dm_buffer *b, blk_status_t status)
  * and uses dm_bufio_mark_buffer_dirty to write new data back).
  */
 static void *new_read(struct dm_bufio_client *c, sector_t block,
-		      enum new_flag nf, struct dm_buffer **bp)
+		      enum new_flag nf, struct dm_buffer **bp,
+		      unsigned short ioprio)
 {
 	int need_submit = 0;
 	struct dm_buffer *b;
@@ -1905,7 +1909,7 @@ static void *new_read(struct dm_bufio_client *c, sector_t block,
 		return NULL;
 
 	if (need_submit)
-		submit_io(b, REQ_OP_READ, read_endio);
+		submit_io(b, REQ_OP_READ, ioprio, read_endio);
 
 	if (nf != NF_GET)	/* we already tested this condition above */
 		wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
@@ -1926,32 +1930,46 @@ static void *new_read(struct dm_bufio_client *c, sector_t block,
 void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
 		   struct dm_buffer **bp)
 {
-	return new_read(c, block, NF_GET, bp);
+	return new_read(c, block, NF_GET, bp, IOPRIO_DEFAULT);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_get);
 
-void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
-		    struct dm_buffer **bp)
+static void *__dm_bufio_read(struct dm_bufio_client *c, sector_t block,
+			struct dm_buffer **bp, unsigned short ioprio)
 {
 	if (WARN_ON_ONCE(dm_bufio_in_request()))
 		return ERR_PTR(-EINVAL);
 
-	return new_read(c, block, NF_READ, bp);
+	return new_read(c, block, NF_READ, bp, ioprio);
+}
+
+void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
+		    struct dm_buffer **bp)
+{
+	return __dm_bufio_read(c, block, bp, IOPRIO_DEFAULT);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_read);
 
+void *dm_bufio_read_with_ioprio(struct dm_bufio_client *c, sector_t block,
+				struct dm_buffer **bp, unsigned short ioprio)
+{
+	return __dm_bufio_read(c, block, bp, ioprio);
+}
+EXPORT_SYMBOL_GPL(dm_bufio_read_with_ioprio);
+
 void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
 		   struct dm_buffer **bp)
 {
 	if (WARN_ON_ONCE(dm_bufio_in_request()))
 		return ERR_PTR(-EINVAL);
 
-	return new_read(c, block, NF_FRESH, bp);
+	return new_read(c, block, NF_FRESH, bp, IOPRIO_DEFAULT);
 }
 EXPORT_SYMBOL_GPL(dm_bufio_new);
 
-void dm_bufio_prefetch(struct dm_bufio_client *c,
-		       sector_t block, unsigned int n_blocks)
+static void __dm_bufio_prefetch(struct dm_bufio_client *c,
+			sector_t block, unsigned int n_blocks,
+			unsigned short ioprio)
 {
 	struct blk_plug plug;
 
@@ -1987,7 +2005,7 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 			dm_bufio_unlock(c);
 
 			if (need_submit)
-				submit_io(b, REQ_OP_READ, read_endio);
+				submit_io(b, REQ_OP_READ, ioprio, read_endio);
 			dm_bufio_release(b);
 
 			cond_resched();
@@ -2002,8 +2020,20 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 flush_plug:
 	blk_finish_plug(&plug);
 }
+
+void dm_bufio_prefetch(struct dm_bufio_client *c, sector_t block, unsigned int n_blocks)
+{
+	return __dm_bufio_prefetch(c, block, n_blocks, IOPRIO_DEFAULT);
+}
 EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
 
+void dm_bufio_prefetch_with_ioprio(struct dm_bufio_client *c, sector_t block,
+				unsigned int n_blocks, unsigned short ioprio)
+{
+	return __dm_bufio_prefetch(c, block, n_blocks, ioprio);
+}
+EXPORT_SYMBOL_GPL(dm_bufio_prefetch_with_ioprio);
+
 void dm_bufio_release(struct dm_buffer *b)
 {
 	struct dm_bufio_client *c = b->c;

include/linux/dm-bufio.h

@@ -64,6 +64,9 @@ void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start);
 void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
 		    struct dm_buffer **bp);
 
+void *dm_bufio_read_with_ioprio(struct dm_bufio_client *c, sector_t block,
+				struct dm_buffer **bp, unsigned short ioprio);
+
 /*
  * Like dm_bufio_read, but return buffer from cache, don't read
  * it. If the buffer is not in the cache, return NULL.
@@ -86,6 +89,10 @@ void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
 void dm_bufio_prefetch(struct dm_bufio_client *c,
 		       sector_t block, unsigned int n_blocks);
 
+void dm_bufio_prefetch_with_ioprio(struct dm_bufio_client *c,
+				sector_t block, unsigned int n_blocks,
+				unsigned short ioprio);
+
 /*
  * Release a reference obtained with dm_bufio_{read,get,new}. The data
  * pointer and dm_buffer pointer is no longer valid after this call.